U.S. patent application number 15/534512 was filed with the patent office on 2017-12-21 for improvements in joint forming devices.
The applicant listed for this patent is Lama D. D. Dekani. Invention is credited to Simon Krizman, Robert Lukezic, Carlo Migli, Valter Svara, William Ernest Taylor Vallance.
Application Number | 20170363125 15/534512 |
Document ID | / |
Family ID | 54848588 |
Filed Date | 2017-12-21 |
United States Patent
Application |
20170363125 |
Kind Code |
A1 |
Migli; Carlo ; et
al. |
December 21, 2017 |
Improvements in Joint Forming Devices
Abstract
A fastening element (20) is provided for use with a tightening
element (14) in a device for forming a joint between two panels
(18,22). The fastening element is elongate and has a head (13) at
one end for engaging the tightening element, an expander (15) at
the other end and a shank (11) extending there between. The
fastening element further comprises a sleeve (10) having an
expandable section (16) at one end extending over the expander,
with the expander operatively engaging the sleeve to cause outward
movement of its expandable section upon axial displacement of the
fastening element relative to the sleeve. The sleeve is provided
with at least one outwardly facing cutting edge (19) on its
expandable section. The cutting edge has sufficient strength to cut
into the panel material in use of the device, when the expandable
section is inserted into a face hole in a first one of the
panels.
Inventors: |
Migli; Carlo; (Lecco,
IT) ; Vallance; William Ernest Taylor;
(Buckinghamshire, GB) ; Svara; Valter; (Izola,
SI) ; Lukezic; Robert; (Portoroz, SI) ;
Krizman; Simon; (Kozina, SI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lama D. D. Dekani |
Dekani |
|
SI |
|
|
Family ID: |
54848588 |
Appl. No.: |
15/534512 |
Filed: |
December 11, 2015 |
PCT Filed: |
December 11, 2015 |
PCT NO: |
PCT/EP2015/079501 |
371 Date: |
June 9, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A47B 96/066 20130101;
F16B 12/2036 20130101; F16B 12/46 20130101; F16B 2012/2018
20130101 |
International
Class: |
F16B 12/20 20060101
F16B012/20 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2014 |
GB |
1422164.2 |
Claims
1. A fastening element for use with a tightening element in a
device for forming a joint between two panels, the fastening
element being elongate and having a head at one end for engaging
said tightening element in use, an expander at the other end, and a
shank extending therebetween, the fastening element further
comprising a sleeve having an expandable section at one end
extending over said expander, with the expander operatively
engaging the sleeve in use to cause outward movement of its
expandable section upon axial displacement of the fastening element
relative to the sleeve, the sleeve having at least one outwardly
facing cutting edge on its expandable section, with the expandable
section of the sleeve being insertable into a face hole in a first
one of the panels, with said cutting edge having sufficient
strength to cut into the panel material in use of the device.
2. A fastening element as claimed in claim 1 wherein the cutting
edge is provided at or near the end of the expandable section of
the sleeve.
3. A fastening element as claimed in claim 2 wherein the fastening
element comprises a flange for engaging the sleeve at a position
spaced from the expander.
4. A fastening element as claimed in claim 3 wherein the flange is
arranged to engage the sleeve at a position within the bore of the
face hole near to its entrance when the fastening element is in its
set position.
5. A fastening element as claimed in claim 1 wherein the end of the
expandable section of the sleeve has an outward flare.
6. A fastening element as claimed in claim 1 wherein said
expandable section of the sleeve comprises two or more individually
moveable finger portions.
7. A fastening element as claimed in claim 6 wherein each finger
portion has a cutting edge.
8. A fastening element as claimed in claim 7 wherein the cutting
edges of the fingers are at different axial positions on the
sleeve.
9. A fastening element as claimed in claim 8 wherein the cutting
edges are set at an inclined angle, so that they are effectively
aligned along one or more helical paths.
10. A fastening element as claimed in claim 8 wherein the finger
portions are moveable hingedly from a position approximately level
with the face of the first one of the panels.
11. A fastening element as claimed in claim 1 wherein apart from
the cutting edge, the expandable section of the sleeve has an
essentially plain outer profile.
12. A fastening element as claimed in claim 11 wherein the
essentially plain outer profile of the expandable section of the
sleeve is cylindrical.
13. A fastening element as claimed in claim 1 wherein the sleeve is
insertable at its other end into an edge hole in the second of the
panels for engagement of the head of the fastening element with the
tightening element in use.
14. A fastening element as claimed in claim 13 and comprising a
reaction surface for holding the axial position of the sleeve
relative to the second panel upon tightening of the device in
use.
15. A fastening element as claimed in claim 14 wherein said
reaction surface is provided by the outside of the tightening
device, with the sleeve being in abutting engagement with it.
16. A fastening element as claimed in claim 1 wherein the sleeve is
formed in two or more individual parts.
17. A fastening element as claimed in claim 16 wherein the
individual parts of the sleeve comprise means for connecting them
together so that the fastening element is able to form an integral
sub-assembly.
18. A fastening element as claimed in claim 1 wherein the sleeve is
made of metal.
19. A fastening element as claimed in claim 18 wherein the sleeve
is made by die-cutting and stamping or pressing.
20-21. (canceled)
Description
[0001] This invention relates to fastening elements for joint
forming devices such as may be used in the furniture industry.
[0002] The invention provides a fastening element for use with a
tightening element in a device for forming a joint between two
panels, the fastening element being elongate and having a head at
one end for engaging said tightening element in use, an expander at
the other end, and a shank extending therebetween, the fastening
element further comprising a sleeve having an expandable section at
one end extending over said expander, with the expander operatively
engaging the sleeve in use to cause outward movement of its
expandable section upon axial displacement of the fastening element
relative to the sleeve, the sleeve having at least one outwardly
facing cutting edge on its expandable section, with the expandable
section of the sleeve being insertable into a face hole in a first
one of the panels, with said cutting edge having sufficient
strength to cut into the panel material in use of the device.
[0003] By way of example, embodiments of the invention will now be
described with reference to the accompanying drawings, in
which:
[0004] FIG. 1 shows in exploded view a first form of fastening
element according to the invention,
[0005] FIG. 2 is a cross-sectional view through a panel joint
showing a device with the fastening element of FIG. 1 in its un-set
condition,
[0006] FIG. 3 shows the panel joint of FIG. 2 in its set
condition,
[0007] FIG. 4 is an enlarged detail of FIG. 3,
[0008] FIG. 5 shows in exploded view a second form of fastening
element according to the invention,
[0009] FIG. 6 is a cross-sectional view through a panel joint
showing a device with the fastening element of FIG. 5 in its un-set
condition,
[0010] FIG. 7 shows the panel joint of FIG. 5 in a partially set
condition,
[0011] FIG. 8 shows the panel joint of FIG. 5 in its fully set
condition, and
[0012] FIG. 9 shows a modified form of dowel for the fastening
elements of FIGS. 1 and 5.
[0013] Devices are known for joining together panels, such as are
used for assembly of furniture panels in factories or at home in
furniture known as "flat pack" or "ready to assemble" or "knock
down" furniture, and which typically comprise a tightening element
in the form of a rotatable cam and a fastening element in the form
of an elongate sleeved dowel. In such devices, the fastening
element is anchorable at one end in a face hole in one panel, with
the cam being mounted in a hole in the other panel and being
operatively engageable with the head of the dowel at its other end.
Conventionally, the dowels are formed of a metal pin, with an
expandable sleeve, typically of plastics material, which can be set
in the face hole by axial displacement of the dowel relative to the
sleeve upon rotation of the cam.
[0014] FIG. 1 illustrates a form of fastening element in which its
sleeve is made of metal. In the preferred form, the sleeve 10 is
made out of sheet metal, for example steel, by die cutting and
stamping or pressing. To facilitate assembly, the sleeve 10 here is
conveniently made in two individual parts 10a, 10b that can be
fitted around the dowel 12. In this case, the two parts 10a, 10b
are each in the form of a semi-cylindrical shell. Connectors, in
this case snap tabs 24, enable the two parts 10a, 10b to attach
together when they are in position on the dowel 12, so that the
sleeve 10 and dowel together form an integral sub-assembly.
[0015] The sleeve could of course be formed in other
configurations, such as by means of a one-piece construction that
is wrapped around the dowel, or using more than two individual
parts. It could also be formed using a different metal, such as
zinc, or a non-metal, such as carbon, or a hybrid composition from
two or more different materials. Also, other processes such as die
casting could be used in the formation of the sleeve.
[0016] The dowel 12 here is of generally known form, with a head 13
at one end to be engaged by a rotatable camming device 14, an
expander 15 at the other end, and a shank 11 extending between the
two. Here, the dowel 12 is conveniently made from rolled steel. The
expander 15 is of generally known form, with a flared, bell-shaped
end. The conical shape of the expander 15 effectively forms a
reaction surface for the outward expansion of the sleeve 10.
[0017] The dowel 12 here additionally has a flange 30 on its shank
11. The flange 30 is designed to engage the sleeve 10, in this case
at the junction of its expandable section 16. Its purpose is to
ensure that the sleeve 10 will be pushed fully into the face hole
17 when the sub-assembly is initially engaged in the panel 18.
[0018] The dowel 12 could of course be formed out of different
materials and in other ways, for example by die casting from zinc
or fabricating from a non-metal such as carbon, or by combinations
of different materials and forming processes.
[0019] The sleeve 10 has two main sections. At one end is its
expandable section 16: this is the part that fits into the face
hole 17 in the first panel 18. The expandable section 16 here is
formed with a number of axially extending slits 25, so that it is
effectively split up into a number of individual fingers 26. The
fingers 26 are designed to facilitate the expansion process. In
this case, the sleeve 10 has four fingers 26, but the number could
of course be more or less.
[0020] The slits 25 extend substantially over the whole of the
expandable section 16, terminating approximately at or just beyond
its junction with the other main section 20 of the sleeve. This
means that the length of the fingers 26 is approximately equal to
the depth of the face hole 17 in the panel 18. What this means in
practice is that in the expansion process, the fingers 26 will tend
to flex with a hinging motion, as will be described in more detail
below.
[0021] At their free ends, each of the fingers 26 presents an
outwardly facing cutting edge 19. The cutting edges 19 extend
around the dowel 12 in an arcuate profile. They are designed to cut
into the material of the panel 18 in the expansion process. They
will not normally have to be specially sharpened for this purpose:
the edge that results from simply cropping the fingers 26 in a die
cutting process will usually be sufficient.
[0022] The fingers 26 are crimped so that their free ends have a
slight outward flare. This assists with presenting the cutting
edges 19 so that they will cut effectively into the material in the
expansion process. It also facilitates the sliding engagement of
the fingers 26 on the expander 15 in the expansion process. The
fingers 26 here otherwise give the expandable section 16 an
essentially plain cylindrical outer profile.
[0023] The expandable section 16 is designed to be readily
insertable into the face hole 17 by hand, but to form a relatively
snug fit within it.
[0024] The other section 20 of the sleeve 10 is designed to fit in
an edge hole 21 in the second panel 22. This section 20 also has an
essentially plain cylindrical outer profile and is designed to be
readily insertable into its hole 21 by hand, but to form a
relatively snug fit within it.
[0025] The edge hole 21 communicates with a face hole 23 in the
second panel 22, with the face hole providing a mount for a
rotatable camming device 14 to engage the head 13 of the dowel 12
in use. The free end of this section 20 of the sleeve 10 terminates
in a reduced diameter section 27. In use, this section 27 abuts
against the outer cylindrical surface of the camming element
14.
[0026] In known manner, when the camming device 14 is rotated about
its axis, its jaws 28 engage with the head 13 of the dowel 12 to
cause axial displacement of the dowel in a direction away from the
first panel 18. Since the sleeve 10 is in abutting engagement with
the outer surface of the camming device 14, it is prevented from
moving. The net result is relative axial movement between the dowel
12 and the sleeve 10.
[0027] FIGS. 3 and 4 show the consequence of this relative movement
between the dowel 12 and the sleeve 10. As will be seen, the axial
displacement of the expander 15 has forced the fingers 26 of the
sleeve 10 to flex outwardly at their free ends, by the action of
the expander 15 on the flared end of the fingers. In so doing, the
cutting edges 19 of the fingers 26 have been forced outwardly and
hence caused to cut into the material of the panel 18. It can be
seen in FIG. 4 how the flexing of the fingers 26 resembles a
hinging motion from a position approximately level with the face of
the panel 18.
[0028] It is intended that the cutting edges 19 will penetrate into
the material to a sufficient depth to prevent the possibility of
the sleeve 10 being simply pulled out of the face hole 17. This
provides a solid point of anchorage for the sleeve 10. Ideally, the
anchorage point is at a position as near to the bottom of the face
hole 17 as possible.
[0029] Panels used in flat pack furniture are typically made out of
composite materials such as wood chip or the like. These typically
contain voids between particulate matter and have little inherent
strength. The aim in this particular design of dowel is to ensure
that its point of engagement with the face hole in the panel will
be at depth. It is also to ensure that the dowel engages the
material with a positive interference fit. In this way, the
effective pull-out resistance of the device is maximised. It may be
preferable for the sleeve to present cutting edges at different
axial positions, so as to cut into the material at different
depths.
[0030] Pull-out resistance is a measure of the pulling force that
is needed to pull a dowel out of a panel and hence is an indication
of the strength of a joint. Conventional expandable sleeve dowel
designs feature ribs or barbs along the length of their sleeves,
effectively creating a series of local interference fits with the
material along the bore of the face hole. The pull-out resistance
of these conventional designs is limited, however, because the
friable nature of the material does not provide strong resistance
to the possibility of the ribs or barbs simply pulling through.
[0031] In the fastener described above, since the cutting edges 19
of the fingers 26 are designed to cut relatively deeply into the
material and at a position at or near to the bottom of the face
hole 17, there will be a significant depth of material between the
point of anchorage of the fastener and the face of the panel 18.
What this means in practice is that the fastener cannot be pulled
out of the face hole 17 without causing significant disintegration
of the panel 18. In particular, pull-out of the fastener will
require a sizeable chunk of material to break away from the panel
18. In effect, therefore, the cutting edges act in the manner of a
crack propagator, so that a typical failure mode will be along
fracture lines A A shown in FIG. 4. The net effect is that the
pull-out resistance of the fastener is considerably greater than
for a conventional fastener.
[0032] It will be appreciated that for the fastener described above
to work effectively, the cutting edge that cuts into the panel has
to be stronger than the panel material and to be able to maintain
its configuration under stress. This will not normally be possible
with conventional fasteners, where the sort of plastic sleeves that
are typically used do not have sufficient strength or rigidity.
Using a metal such as steel to fabricate the sleeve ensures that
there will be sufficient strength and rigidity. However, it will be
understood that other materials could equally well be used, even
plastics, providing it is is of a grade with sufficient strength
and rigidity.
[0033] The form of fastener seen in FIG. 5 is essentially similar
to that shown in FIG. 1. In this case, however, the expandable
section 51 of the sleeve 50 is not plain, but is provided with
additional barbs 52. The sleeve 50 still comprises flexible fingers
53 with cutting edges 54 at their free ends that operate in the
expansion process in the same manner as described above. The barbs
52 do not interfere with this operation. Instead, their purpose is
to engage the bore of the face hole 17 in the panel 18
substantially throughout its depth and hence provide additional
stability to the anchorage of the fastener in the panel.
[0034] As will be seen in FIGS. 6, 7 and 8, another difference from
the jointing device described above is in the design of the camming
device 60. In this case, the camming device 60 is provided with a
tapering groove 61 in its outer circumferential surface. The
purpose of the groove 61 is to allow for a certain degree of axial
displacement of the sleeve 50 during the joint forming process. In
known manner, initial rotation of the camming device 60 causes the
expansion process to anchor the sleeve 50 in the face hole 17 in
its panel 18, as seen in FIG. 7. Further rotation of the camming
device 60 then pulls both the dowel 70 and the sleeve 50, thus
pulling the panel 18 with it and hence creating a tight joint.
[0035] Flat pack furniture is typically expected to be capable of
being disassembled and re-assembled, so it is preferable to be able
to extract the cams and/or dowels of the fasteners described above
from their panels. For the dowels to be capable of being pulled out
of their face holes, the fingers of their sleeves would have to
retract sufficiently for the cutting edges to clear the bore of the
face hole. In practice, depending on materials used, this is
unlikely to occur without special provision. Accordingly, to
facilitate extraction, the fingers are preferably cut at a slight
angle, rather than square, and at slightly spaced apart axial
positions, in order that their cutting edges are effectively
aligned along a helical path. This then allows the possibility for
the dowel and sleeve to be "unscrewed" out of the face hole, with
the cutting edges effectively cutting a helical groove in the bore
of the face hole in the process, somewhat in the manner of a screw
thread.
[0036] Alternatively, or in addition, it might be possible to
include a mechanism for urging retraction of the fingers of the
sleeve to facilitate removal of the dowel from the face hole on
disassembly, for example by suitably configuring the sleeve at its
point of engagement with the flange on the shank of the dowel.
[0037] A preferred modification to the dowels described above is
seen in FIG. 9. The modification comprises a flange 80 on the shank
81 of the dowel 82. As will be seen, the flange 80 is located on
the lower section of the dowel 81. Specifically, the flange 80 is
spaced from the expander region 83 of the dowel 82 by a distance
less than the depth of the face hole 84 in which the fastening
element is located. The flange 80 is designed to engage the fingers
85 of the sleeve 86 near the entrance to the face hole 84 when the
fastening element is in its set position (as seen in FIG. 9). The
purpose of the arrangement is to ensure that the fingers 85 of the
sleeve 86 will fit snugly in the bore of the face hole 84. This
eliminates or at least substantially reduces the possibility for
lateral "play", ie transverse shearing movement between the two
panels 87, 88 (illustrated by arrow A in FIG. 9).
* * * * *